internal/coverage: fix comment dupword, error typo

- Correct duplicated word in comments.
- Fix typo in error message.

Change-Id: I688d723ea3ac4d0b1981afd747e4b2df00c81448
Reviewed-on: https://go-review.googlesource.com/c/go/+/485016
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>

src/internal/coverage/defs.go

@@ -4,7 +4,7 @@
 
 package coverage
 
-// Types and constants related to the output files files written
+// Types and constants related to the output files written
 // by code coverage tooling. When a coverage-instrumented binary
 // is run, it emits two output files: a meta-data output file, and
 // a counter data output file.
@@ -172,7 +172,7 @@ type FuncDesc struct {
 // jumps or control transfers). An "intraline" unit corresponds to a
 // logical clause nested within some other simple unit. A simple unit
 // will have a zero Parent value; for an intraline unit NxStmts will
-// be zero and and Parent will be set to 1 plus the index of the
+// be zero and Parent will be set to 1 plus the index of the
 // containing simple statement. Example:
 //
 //	L7:   q := 1

src/internal/coverage/pods/pods_test.go

@@ -136,7 +136,7 @@ o2/covcounters.aaf2f89992379705dac844c0a2a1d45f.42.3 o:1
 		dbad := "/dev/null"
 		_, err = pods.CollectPods([]string{dbad}, true)
 		if err == nil {
-			t.Errorf("exected error due to unreadable dir")
+			t.Errorf("executed error due to unreadable dir")
 		}
 	}
 }